Infrared floodlighting has significant application to security systems where it is often desirable to illuminate areas with infrared radiation not visible to the unaided human eye. Floodlighting of this type is particularly advantageous when used with closed circuit television surveillance equipment, but can also be used with direct passive viewing devices. Conventional infrared floodlights of the lens or reflector type typically utilize visible light-absorbing and infrared-transmitting filters located in front of the floodlight's lens to filter out visible light and pass infrared radiation therethrough. Since appreciable heat is absorbed by such filters, these known floodlights generally have been relative large for the wattages involved in order to minimize the power density at the filters. At times, forced cooling has been required. With very few exceptions, cost has limited the filters to the form of flat plates, which in turn increases the difficulty of producing wide beam spreads due to the increased absorption of rays which do not impinge normal to the filter. Consequently, not only is the visible radiation absorbed by such filters but certain infrared bands within the infrared spectrum are absorbed as well.
Accordingly, a need exists for an infrared floodlight assembly which is capable of handling the large radiant power required for such applications as infrared floodlight surveillance. It is believed that such a floodlight would constitute a significant advancement in the art.